It is generally desirable to be able to use a toilet without touching the toilet or at least touching the toilet as little as possible. For health reasons, both real and imagined, it is especially desirable to minimize or eliminate touching of a toilet or any of its components by hand. Hands come into contact with not only food and eating utensils, but with other people. It is well known that toilets harbor microorganisms for numerous diseases from dysentery to hepatitis. Moreover, it is well known that many people are not in the habit of washing their hands after using a toilet. Consequently, avoidance of touching the surfaces of toilets can help break disease transmission chains. While having touch free toilets in homes is certainly desirable for many reasons, public touch free toilets are highly desirable because the users do not know one another and are not in constant contact and proximately with one another, other than through common toilet use.
It is of course, highly desirable to have automatic flush which are usable with newly manufactured toilets and with the millions of toilets, both public and private, which already exist. Practically all toilets which use a flush tank have overflow tubes and flush valves which close flush tank outlets that dump water at a rapid rate from the flush tanks into toilet bowls. In view of these considerations, there is a need for automatic flushing which is readily adaptable to both original equipment and existing installations.
Automatic flushing systems often use a linear mechanical actuator to provide the mechanical force to open a flush valve. Although the direction of the produced force from a linear mechanical actuator is generally linear, the amount of force, over the mechanical actuator's dynamic range, may not be linear. A force must be applied to mechanical loads such as those required for flush valve lifting. Additionally, while the direction of the required force is generally linear, the amount of force required, over its dynamic range, may not be linear.
It is often found that the length of the throw and the non-linear dynamic force characteristics of a linear mechanical actuator cannot be efficiently matched to a required linear mechanical load, such as a flush valve in a toilet. Thus there is a need for a simple and easily adaptable device that can properly match the force provided by a linear actuator to a variable mechanical load, such as raising a flush valve.